A wide variety of detection devices, including but not limited to sensors, have been developed and manufactured for a diverse number of applications. The term "sensor" is but one example of the general term, "detection devices." Detection devices in the nature of sensors are used to locate, monitor and detect the presence both of matter and energy (the energy including but not limited to sound, light, radio and radar waves). As is known to those of skill in the art, some sensors also are called "switches," referring not only to devices for opening and closing electrical circuits, but also to electronic circuits for switching between two independent inputs. Switches may also be referred to as "motion" switches and "zero speed" switches.
Sensors are widely used in industry. Sensors are used, for example, to monitor and verify starting, operation, and stopping of machines, machine elements, and machine components. Uses for sensors include monitoring machines to anticipate over-loading, and protection against jamming of interrelated machine components and elements. Sensors also frequently are used to monitor speed, velocity, acceleration, and deceleration of machine elements, including reciprocating, rotating and rotatable gears, shafts, and cooperatively rotating and linearly moving systems like conveyors, fans, tachometers, counting systems, alarms, and other machines and machine elements.
A widely used form of sensor is the proximity sensor, or proximity switch. Proximity sensors are used in situations requiring fast, maintenance-free, wear resistant detection of objects, often in automation processes. Proximity sensors are available in at least two forms, inductive proximity sensors, and capacitive proximity sensors. Without physical contact between a sensor and an object to be detected, and independent of form, inductive proximity switches are available to detect all ferrous and non-ferrous metallic objects within an active zone of a proximity sensor. Capacitive proximity sensors may detect nonmetallic substances such as water, glass, plastics, paper, wood, and other substances.
Proximity sensors are useful because they require no physical contact with a moving or rotating machine element to perform the sensors' monitoring functions. As is now well known in the art, many inductive proximity sensors operate on the principle of an Eddy-current damped oscillator. For example, an oscillator circuit coil, with ferrite in the coil, may generate an electromagnetic field, often referred to as an "active zone" of a proximity sensor. When a metallic object enters an active zone of a sensor, the electrical state of the oscillator may change, and oscillation may slow or stop. When a metallic object comes within a certain distance of a proximity switch, the metallic object causes a modification of the current consumption in a sensor. The modification is detected, often by a trigger circuit, which in turn modifies the output stage of the sensor. If a metallic object is removed from an active zone, the oscillator circuit oscillates again, and the initial state of the sensor is reestablished. The influence on the state of the oscillator is a function of both the distance between the metallic object and the sensor, and the material used to construct the metallic object intruding into the active zone of the sensor.
The principles on which capacitive proximity sensors operate are different due to the nonmetallic nature of objects which may intrude into the active zone of a capacitive sensor. Sensors also exist which are described as "Namur-type" proximity sensors, where "Namur" means "Normen-Arbeitsgemeinschaft fur Mess- und Regeltechnic." Inductive and capacitive Namur-type proximity switches basically consist of an oscillator circuit without an amplifier.
All forms of proximity sensors, or switches, are useful in monitoring operation of machine elements because proximity sensors can perform the sensors' monitoring functions without requiring physical contact with the machine element being monitored. A proximity sensor need only be placed in a position adjacent the machine element to be monitored, and need not physically contact or touch the machine element, whether static, moving, reciprocating, or rotating. A proximity sensor will function by merely being adjacent to an object. Physical contact with the object is not necessary. Therefore, proximity sensors are used in a wide variety of applications to monitor operation of machine elements.
Machine elements to be monitored by one or more sensors may include individual components of machines. For example, in connection with a conveyor system, one or more machines may be used to cause the conveyor system to operate. The one or more machines may be equipped with reciprocable or rotatable or rotating machine elements such as shafts. An operator may want to monitor, for example, a rotatable or rotating shaft to assess operation of an individual machine or a machine system in which the machine is a component. As industry reliance on sensors has increased, reliance on human observation of machine elements has decreased. Further, many environments in which machines operate require substantially uninterrupted operation, day and night, without regard to weekends or holidays. Industry relies on sensors to monitor substantially continuous operation of machine elements.
Gravity, friction, velocity of rotation, and the consequent load forces applied to bearings, driven shafts, and other components of driving and driven machines (collectively, "machine elements") may contribute to wear, material fatigue and degradation of machine elements. Monitoring a machine element, such as a rotatable rotor, axle or shaft (collectively, "shaft"), therefore, becomes necessary to enable a user to detect not only reciprocating or rotating operation of the machine element, but also to determine whether and to what extend a machine element such as a shaft may be wearing, fatiguing, or degrading. High speed circular rotation of shafts mounted in bearings gives rise to a force toward the center known as centripetal force, a force which is reacted to by centrifugal reaction. Angular velocity and angular acceleration of machine elements subjected not only to high velocity but significant loads also induce gyroscopic effects on shafts spinning rapidly and under significant load about the geometric axis of the shaft. As is commonly known, when two forces act on a shaft, a torque is formed whose vector along the x-axis which will produce a rotation about the y-axis, known as "precession" having significant angular velocities. The gyroscopic effect and torque also contribute to inducing wear of shafts and bearings in which shafts are located. In any rotational or reciprocating machine where accelerations and velocities are present, unbalanced forces may lead to stresses and vibrations. Further, if the speed of a shaft or rotor is slowly increased from rest, there will be a speed where the deflection increases suddenly, a phenomenon known as "whirling." A shaft which is balanced will rotate around the center of gravity of the shaft. However, if the shaft rotates at an angular velocity, the shaft will deflect a distance from the center of gravity due to centripetal reaction. Rotation also may induce undamped free vibrations. All of these forces and phenomena may contribute to rapid and excessive wear among machine elements, particularly in machine elements subjected to high forces. Excessive and rapid degradation and wear of machine components, including machine elements such as rotating shafts, may cause significant down time, expensive delays in repair and replacement of machine elements, and delays in use of the systems of which the machine is a component, particularly when a machine's worn element must be identified, inspected, removed and replaced. Frequent replacement of machines and machine elements causes significant expense to the operator. Such delays, costs and expenses are compounded if the apparatus is located at a remote site, or is part of a system which is expected to operate substantially uninterruptedly.
Therefore, the importance of a detection device such as a sensor is significant. A problem, however, is properly locating or positioning a sensor in proximity to the moving or rotating machine element. An additional problem is relocating, or repositioning, sensors as machines and machine elements are moved to a new position on assembly lines, on conveyor systems, and in other operating environments. Relocation or repositioning of a machine or machine element may be slight, but may be frequently done to adjust the system in which the machine is a component for a new and possibly temporary application. There is a need to position a detection device, such as a sensor for monitoring operation of a machine element. There also is a need to reposition a detection device easily and quickly with assurance that a detection device will remain properly positioned to perform its detection and monitoring function after relocation.
A problem to be solved, therefore, is to position a detection device to monitor operation of a machine element. Another problem to be solved is to position a detection device, including any one of a variety of sensors, to enable the sensor to substantially continuously monitor a reciprocable or rotatable machine element including, but not limited to, a rotating machine shaft. Another problem to be solved is to position a detection device in the proximity of a rotatable or rotating machine element, such as a shaft, to enable a sensor to monitor the fact of rotation, or the speed of rotation, or the velocity of rotation, of a machine element from zero speed of rotation through any speed of rotation, although no human operator may be monitoring operation of the machine or the machine element, regardless of the time of day or night.
An additional problem to be solved includes providing an apparatus for positioning one or more detection devices, including one or more sensors, for monitoring rotation of a machine element in such a way that the apparatus may be easily and readily moved or relocated to satisfy changed applications, needs, or combinations of machines in which a machine element is located.
What also is needed is a variety of ways to provide a carriage for components of the apparatus, including, but not limited to, an open platform, a partially enclosed housing, or a substantially enclosed housing.
In light of the above, it is an object of the present invention to provide an apparatus for positioning a detection device for monitoring a rotatable machine element.
It is another object of the present invention to provide an apparatus for positioning a detection device for monitoring a reciprocable or rotatable machine element, including but not limited to, a shaft.
Yet another object of the present invention is to provide an apparatus for positioning a detection device for monitoring a rotatable machine element that locates or positions a sensor in proximity to the moving or rotating machine element.
An additional object of the present invention is to provide an apparatus for positioning a detection device for monitoring a rotatable machine element that can be easily and readily relocated and repositioned as a machine and machine elements are moved or relocated.
In addition, it is an object of the present invention to provide an apparatus for positioning a detection device for monitoring a rotatable machine element which itself may be repositioned and relocated from one machine element to another, and to do so easily and quickly, with assurance that the detection device will remain properly positioned to perform the detection and monitoring function of the detection device, including a sensor.
It is yet another object of the present invention to provide an apparatus for positioning a detection device for monitoring a rotatable machine element to enable the sensor to continuously monitor a rotatable and rotating machine element including, but not limited to, rotating machine shafts.
Another object of the present invention is to provide an apparatus for positioning a detection device for monitoring a rotatable machine element in the proximity of a rotatable or rotating machine element, such as a shaft, to enable any one of a variety of sensors to monitor the fact of rotation, or the speed of rotation, or the velocity of rotation, of a machine element from zero speed of rotation through any speed of rotation, although no human may be monitoring operation of the machine or the machine element, and regardless of the time of day or night.
An additional object of the present invention is to provide an apparatus for positioning a detection device for monitoring a rotatable machine element adjacent a device for monitoring rotation of a machine element in such a way that the apparatus may be easily and readily moved or relocated to satisfy changed applications, needs, and combinations of the machine in which the machine element is rotatable or rotating.
It is also an object of the present invention to provide an apparatus for positioning a detection device for monitoring a rotatable machine element which may include a variety of ways to provide a carriage for the components of the apparatus, including, but not limited to, an open platform, a partially enclosed housing, or a substantially fully enclosed housing.
It is also an object of the present invention to provide an apparatus for positioning a detection device for monitoring a rotatable machine element which can be connected or interconnected to a computer or microprocessor to enable an operator at a site remote from the detection device to receive information and data about operation of the apparatus and of the rotatable machine element.
Yet another object of the present invention is to provide an apparatus for positioning a detection device for monitoring a rotatable machine element, and a method for making the apparatus, which respectively are easy to use and to practice, and which are cost effective for their intended purposes.
These and other objects, features, and advantages of such an apparatus for positioning a detection device for monitoring a rotatable machine element will become apparent to those skilled in the art when read in conjunction with the accompanying following detailed description, drawing figures, and appended claims.